Polarization analyzing system, exposure method, and method for manufacturing semiconductor device

ABSTRACT

A polarization analyzing system includes a data collector collecting information on resist patterns formed over step patterns by first and second lights, the first and second lights being polarized parallel and perpendicular to the step patterns, a residual resist analyzer obtaining first and second relations between a ratio of a space to a line width of the resist patterns and the first and second residues, the first and second residues remaining at orthogonal points of the step patterns and the resist patterns, and a direction chooser choosing an optimum polarization direction reducing residues by comparing the first and second relations.

CROSS REFERENCE TO RELATED APPLICATIONS AND INCORPORATION BY REFERENCE

This application is based upon and claims the benefit of priority fromprior Japanese Patent Application P2004-033376 filed on Feb. 10, 2004;the entire contents of which are incorporated by reference herein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to lithography techniques and inparticular to a polarization analyzing system, an exposure method, and amethod for manufacturing a semiconductor device

2. Description of the Related Art

To maximize integration of device components in an availablesemiconductor wafer area to fit more components in the same area,increased IC miniaturization is utilized. Reduced dimension of featuresformed on the semiconductor wafer are needed for increased integrationdensity to meet the requirement of very large scale integration (VLSI).As the dimensions of the features are reduced, the features must bealigned with a greater and greater degree of precision. In amanufacturing process for the MOS transistor, a gate electrode alsocontinues to shrink in size over time. Therefore, increased precisenessin an ion implantation process is required. Such gate electrode of theMOS transistor is disposed on the wafer like a step pattern extended ina predetermined direction. When a resist pattern, perpendicular to thestep pattern is formed over the step pattern on the wafer by lithographyprocess, residual resists may remain at an orthogonal point of the steppattern and the resist pattern, or a line width of the resist, patternmay be decreased at the orthogonal point. In Japanese Patent Laid-OpenPublication No. Hei5-226226, a method for preventing the decrease of theline width is described. In the method, an illumination light ispolarized such that the electric field of the illumination light is onlyperpendicular to the step pattern. However, a method for reducing theresidual resist has not been proposed. Although the optical proximityeffect correction (OPC) method is widely spread to reproduce a designedcircuit pattern on the wafer, such OPC method has not been effective inreducing the residual resist remaining at the orthogonal point of thestep pattern and the resist pattern.

SUMMARY OF THE INVENTION

An aspect of present invention inheres in a polarization analyzingsystem according to an embodiment of the present invention. Thepolarization analyzing system includes a data collector configured tocollect an information on resist patterns formed over step patternsdisposed on wafers by first and second lights, respectively, the resistpatterns being perpendicular to the step patterns, the first and secondlights being polarized parallel and perpendicular to the step patterns,respectively, a residual resist analyzer configured to obtain first andsecond relations between a ratio of a space to a line width of theresist patterns and amounts of first and second residual resists on thewafers, respectively, the first and second residual resists remaining atorthogonal points of the step patterns and the resist patterns formed bythe first and second lights, respectively, and a direction chooserconfigured to choose an optimum polarization direction reducing residualresists by comparing the first and second relations.

Another aspect of the present invention inheres in an exposure methodaccording to an embodiment of the present invention. The exposure methodincludes forming a first resist pattern over, a step pattern disposed ona wafer by a first light, the first resist pattern being perpendicularto the step pattern, the first light being polarized parallel to thestep pattern, obtaining a first relation between a ratio of a space to aline width of the first resist pattern and an amount of a first residualresist on the wafer, the first residual resist remaining at anorthogonal point of the step pattern and the first resist pattern,forming a second resist pattern over the step pattern disposed on thewafer by a second light, the second resist pattern being perpendicularto the step pattern, the second light being polarized perpendicular tothe step pattern, obtaining a second relation between a ratio of a spaceto a line width of the second resist pattern and an amount of a secondresidual resist on the wafer, the second residual resist remaining at anorthogonal point of the step pattern and the second resist patternformed by the second light, and choosing an optimum polarizationdirection reducing residual resists by comparing the first and secondrelations.

Yet another aspect of the present invention inheres in a method formanufacturing a semiconductor device according to an embodiment of thepresent invention. The method for manufacturing the semiconductor deviceincludes preparing first and second wafers on which first and secondstep patterns extended in a direction are disposed, respectively,coating first and second resists over the first and second step patternson the first and second wafers, respectively, and inserting each of thefirst and second wafers into an exposure tool, projecting an image of areticle onto each of the first and second resists by first and secondlights to form first and second resist patterns, respectively, the firstand second resist patterns being perpendicular to the first and secondstep patterns, respectively, the first and second lights being polarizedparallel and perpendicular to the first and second step patterns,respectively, obtaining a first relation between ratio of a space to aline width of the first resist pattern and an amount of a first residualresist on the first wafer, the first residual resist remaining at anorthogonal point of the first step pattern and the first resist pattern,obtaining a second relation between a ratio of a space to a line widthof the second resist pattern and an amount of a second residual resiston the second wafer, the second residual resist remaining at anorthogonal point of the second step pattern and the second resistpattern, determining an optimum polarization direction reducing residualresists by comparing the first and second relations, preparing a thirdwafer on which a third step pattern extended in the direction isdisposed and coating a third resist over the third step pattern on thethird wafer, and inserting the third wafer into the exposure tool andprojecting a device pattern onto the third wafer by using a lightpolarized in the optimum polarization, direction.

Yet another aspect of the present invention inheres in the method formanufacturing these semiconductor device according to an embodiment ofthe present invention. The method for manufacturing the semiconductordevice includes simulating formations of first and second resistpatterns over first and second step patterns extended in a direction onfirst and second wafers by exposing resists to first and second lights,respectively, the first and second resist patterns being perpendicularto the first and second step patterns, respectively, the first andsecond, lights being polarized parallel and perpendicular to the firstand second step patterns, respectively, obtaining a first relationbetween ratio of a space to a line width of the first resist pattern andan amount of a first residual resist on the first wafer, the firstresidual resist remaining at an orthogonal point of the first steppattern and the first resist pattern, obtaining a second relationbetween a ratio of a space to a line width of the second resist patternand an amount of a second residual resist on the second wafer, thesecond residual resist remaining at an orthogonal point of the secondstep pattern and the second resist pattern, determining an optimumpolarization direction reducing residual resists by comparing the firstand second relations, preparing a third wafer on which a third steppattern extended in the direction is disposed and coating a third resistover the third step pattern on the third wafer, and inserting the thirdwafer into the exposure tool and projecting a device pattern onto thethird wafer by using alight polarized in the optimum polarizationdirection.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram of a polarization analyzing system in accordancewith an embodiment of the present invention;

FIG. 2 illustrates an exposure tool in accordance with the embodiment ofthe present invention;

FIG. 3 is a first plan view of a polarizer, in accordance with theembodiment of the present invention;

FIG. 4 is a second plan view of the polarizer in accordance with theembodiment of the present invention;

FIG. 5 is an enlarged plan view of a first resist pattern in accordancewith the embodiment of the present invention;

FIG. 6 is a perspective view of the first resist pattern in accordancewith the embodiment of the present invention;

FIG. 7 is a plan view of a first testing reticle in accordance with theembodiment of the present invention;

FIG. 8 is a plan-view of a second testing reticle in accordance with theembodiment of the present invention;

FIG. 9 is a plan view of a third testing reticle in accordance with theembodiment of the present invention;

FIG. 10 is a perspective view of the first wafer in accordance with theembodiment of the present invention;

FIG. 11 is a first plan view of the first resist pattern in accordancewith the embodiment of the present invention;

FIG. 12 is a second plan view of the first resist pattern in accordancewith the embodiment of the present invention;

FIG. 13 is a third plan view of the first resist pattern in accordancewith the embodiment of the present invention;

FIG. 14 is a sample graph of a ratio of a space to a line width of aresist pattern versus an amount of residual resists in accordance withthe embodiment of the present invention;

FIG. 15 is a first flowchart depicting a method for manufacturing asemiconductor device in accordance with the embodiment of the presentinvention;

FIG. 16 is a second flowchart depicting the method for manufacturing thesemiconductor device in accordance with the embodiment of the presentinvention;

FIG. 17 is a first plan view of a polarizer in accordance with amodification of the embodiment of the present invention;

FIG. 18 is a second plan view of the polarizer in accordance with themodification of the embodiment of the present invention;

FIG. 19 illustrates an exposure tool in accordance with the modificationof the embodiment of the present invention; and

FIG. 20 is a flowchart depicting a method for manufacturing thesemiconductor device in accordance with the modification of theembodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Various embodiments of the present invention will be described withreference to the accompanying drawings. It is to be noted that the sameor similar reference numerals are applied to the same or similar partsand elements throughout the drawings, and the description of the same orsimilar parts and elements will be omitted or simplified.

With reference to FIG. 1, a polarization analyzing system includes acentral processing unit (CPU) 100. The CPU 100 includes a data collector321, a residual resist analyzer 323, and a direction chooser 324. Thedata collector 321 is configured to collect information on resistpatterns formed over step patterns disposed on wafers by first andsecond lights, respectively. Here, each of the resist patterns isperpendicular to each of the step patterns. The first and second lightsare polarized parallel and perpendicular to the step patterns,respectively.

The residual resist analyzer 323 is configured to obtain first andsecond relations between a ratio of a space to a line width of theresist patterns and amounts of first and second residual resists on thewafers, respectively. Here, the first and second residual resists remainat orthogonal points of the step patterns and the resist patterns formedby the first and second lights, respectively. The direction chooser 324is configured to choose an optimum polarization direction reducingresidual resists by comparing the first relation and the secondrelation.

An exposure tool 300 is connected to the CPU 100. With reference to FIG.2, the exposure tool 300 includes a light source 3 which irradiatesillumination light such as a krypton fluoride (KrF) excimer laser with awavelength of 248 nm, a fly-eye lens 4 which receives the illuminationlight irradiated from the light source 3, an illumination aperture 5which shields marginal rays, a polarizer holder 6 which holds apolarizer polarizing the illumination light, a reticle blind 7 whichdefines an exposure field of the polarized illumination light, areflecting mirror 8 which changes the traveling direction of thepolarized illumination light, a condenser lens 9 which condenses thepolarized illumination light reflected by the reflecting mirror 8, areticle stage 11 placed below the condenser lens 9, a projection lens 13which is placed below the reticle stage 11 and receives the polarizedillumination light, and a wafer stage 15 placed below the projectionlens 13.

The illumination light irradiated from the light source 3 penetratesinto each of a plurality of lenses 104 a, 104 b, 104 c and 104 d whichform the fly-eye lens 4. The illuminati on light transmitted througheach of the plurality of lenses 104 a-104 d is irradiated onto an entiresurface of an exposure field of a reticle placed on the reticle stage 11through the polarizer held by the polarizer holder 6, the reflectingmirror 8 and the condenser lens 9. Hence, on the reticle, the polarizedillumination lights transmitted through the plurality of lenses 104a-104 d of the fly-eye lens 4 are superimpose don the others. Therefore,an even illumination is provided on the reticle.

With reference next to FIG. 3, the polarizer held by the polarizerholder 6 includes a polarizing film 42 which confines an electric fieldof the illumination light to a direction indicated by arrows.Alternatively, as shown in FIG. 4, the polarizer may further include alight-shielding portion 40 on the center portion of a polarizing film41. In FIG. 2, a polarizer holder rotator 66 is connected to thepolarizer holder 6. The polarizer holder rotator 66 rotates thepolarizer holder 6 holding the polarizer shown in FIG. 3 or FIG. 4.Therefore, the polarization direction of the polarized illuminationlight can be rotated around an optical axis in the exposure tool 300shown in FIG. 2.

A reticle stage aligner 111 is connected to the reticle stage 11. Thereticle stage aligner 111 moves the reticle stage 11 and determines theposition where the reticle stage 11 is to be placed. Each of the testingreticles for quantifying the amount of the residual resists remaining atthe orthogonal points of the step patterns and the resist patterns ismounted on the reticle stage 11.

With reference to FIGS. 5 and 6, explanation for the amount of theresidual resists remaining at the orthogonal points of the step patternsand the resist patterns is described. A first step pattern 16 shown inFIG. 5 extended in a predetermined direction is disposed on a firstwafer 14 to be mounted on the wafer stage 15 shown in FIG. 2. Further, afirst resist pattern 77 a perpendicular to the first step pattern 16 isformed on the first wafer 14. In the proximity of an orthogonal point ofthe first step pattern 16 and the first resist pattern 77 a, each of thespreading portions 57 a, 57 b, 57 c and 57 d of the first residualresists remains after a lithography process for forming the first resistpattern 77 a. Here, a perpendicular distance from an edge of the firstresist pattern 77 a to an edge of the spreading portion 57 a is definedas an amount of first residual resist “d₁”. Similarly, a perpendicular,distance from an edge of the first resist pattern 77 a to an edge of thespreading portion 57 b is defined as an amount of first residual resist“d₂”, a perpendicular distance from an edge of the first resist pattern77 a to an edge of the spreading portion 57 c is defined as an amount offirst residual resist “d₃”, and a perpendicular distance from an edge ofthe first resist pattern 77 a to an edge of the spreading portion 57 dis defined as an amount of first residual resist “d₄”.

Examples of the testing reticles for quantifying the amount of theresidual resists are shown in plan views of FIGS. 7, 8, and 9. A firsttesting reticle shown in FIG. 7 includes a transparent mask substrate 90and a light-shielding film 70 deposited on the mask substrate 90. Aquartz glass can be used for the mask substrate 90 and the chromium (Cr)can be used for the light-shielding film 70, for example. In thelight-shielding film 70, a plurality of transparent portions 80 a, 80 b,80 c, 80 d, 80 e and 80 f are provided. Each shape of the transparentportions 80 a-80 f is a rectangular of the same width “W₁” congruentwith the others. Each of the transparent portions 80 a-80 f is arrangedin parallel to the others at a pitch “T₁” equal to “W₁”. The polarizedillumination light penetrates the mask substrate 90 through each of thetransparent portions 80 a-80 f.

A second testing reticle shown in FIG. 8 includes a mask substrate 91and a light-shielding film 71 deposited on the mask substrate 91. In thelight-shielding film 71, a plurality of transparent portions 81 a, 81 b,81 c, 81 d and 81 e are provided. Each shape of the transparent portions81 a-81 e is a rectangular of the same width “W₂” congruent with theothers, which is arranged at the pitch “T₁” in the light-shielding film71. Each width “W₂” of the transparent portions 81 a-81 e is twice aslong as the pitch “T₁”. The polarized illumination light penetrates themask substrate 91 through each of the transparent portions 81 a-81 e.

A third testing reticle shown in FIG. 9 includes a mask substrate 92 anda light-shielding film 72 deposited on the mask substrate 92. In thelight-shielding film 72, a plurality of transparent portions 82 a, 82 b,82 c and 82 d are provided. Each shape of the transparent portions 82a-82 d is a rectangular of the same width “W₃” congruent with theothers, which is arranged at the pitch “T₁” in the light shielding film72. Each width “W₃” of the transparent portions 82 a-82 d is six timesas long as the pitch “T₁”. The polarized illumination light penetratesthe mask substrate 92 through each of the transparent portions 82 a-82d.

With reference again to FIG. 2, a wafer stage aligner 115 is connectedto the wafer stage 15. The wafer stage aligner 115 moves the wafer stage15 to determine the position where the wafer stage 15 is to be placed.The first wafer 14 shown in FIG. 10 may be mounted on the wafer stage15. The first step pattern 16 is displaced on the first wafer 14. Agateelectrode extended in a predetermined direction “Y” is an example of thefirst step pattern 16. Also, a first resist 30 is coated on the firstwafer 14. The first resist 30 is to be exposed with the polarizedillumination light by the exposure tool 300.

FIG. 11 shows a plan view of the first wafer 14 subjected to aprojection of an image of the first testing reticle shown in FIG. 7 bythe first light and a development of the first resist 30. Here, thefirst light is polarized such that the electric field of theillumination light is parallel to the first step pattern 16 on the firstwafer 14 by the polarizer. A plurality of first resist patterns 77 a, 77b, 77 c, 77 d, 77 e and 77 f extended in a direction “X” perpendicularto the first step pattern 16 are formed over the first step pattern 16on the first wafer 14. Each line width of the first resist patterns 77a-77 f is “L”. The first resist patterns 77 a-77 f are arranged at aspace “S₁” equal to the line width “L”.

FIG. 12 shows a plan view of the first wafer 14 subjected to aprojection of an image of the second testing reticle shown in FIG. 8 bythe first light and a development of the first resist 30. A plurality offirst resist patterns 87 a, 87 b, 87 c and 87 d extended in thedirection “X” perpendicular to the first step pattern 16 are formed overthe first step pattern 16 on the first wafer 14. Each line width of thefirst resist patterns 87 a-87 d is “L”. The first resist patterns 87a-87 d are arranged at a space “S₂” that is three times as long as theline width “L”.

FIG. 13 shows a plan view of the first wafer 14 subjected to aprojection of an image of the third testing reticle shown in FIG. 9 bythe first light and a development of the first resist 30. A plurality offirst resist patterns 97 a, 97 b and 97 c extended in the direction “X”perpendicular to the first step pattern 16 are formed over the firststep pattern 16 on the first wafer 14. Each line width of the firstresist patterns 97 a-97 c is “L”. The first resist patterns 97 a-97 care arranged at a space “S₃” that is six times as long as the line width“L”.

Also, second resist patterns are formed over second step patternsdisposed on second wafers, respectively, by the second light. Here, eachshape of the second step patterns and the second wafers is same as theshape of the first step pattern 16 and the first wafer 14 shown in FIG.10. The second light is polarized such that the electric field of theillumination light is perpendicular to each of the second step patternson the second wafers by the polarizer. The second resist patterns areformed in the following manner. Each of the second wafers is coated witha second resist in a similar way shown in FIG. 10. Thereafter, eachimage of the first, second, and third testing reticles shown in FIGS. 7,8, and 9, respectively, is projected onto the second resist with thesecond light. By developing the second resist, the second resistpatterns are formed. Drawings of the second resist patterns formed bythe first, second, and third testing reticles shown in FIGS. 7, 8, and 9are similar to the drawings of the first resist patterns shown in FIGS.11, 12, and 13, respectively. Therefore, the drawings of the secondresist patterns are omitted.

At the orthogonal point of the first step pattern 16 shown in FIG. 11and the first resist pattern 77 a, the spreading portions 57 a-57 d ofthe first residual resist remain on the first wafer 14 as shown in FIGS.5 and 6. Although illustrations are omitted, such spreading portions ofthe first residual resist also remain at orthogonal points of the otherfirst resist patterns 77 b-77 f shown in FIG. 11 and the first steppattern 16, at orthogonal points of the first resist patterns 87 a-87 dshown in FIG. 12 and the first step pattern 16, and at orthogonal pointsof the first resist patterns 97 a-97 c shown in FIG. 13 and the firststep pattern 16. Further, spreading portions of the second residualresists remain at orthogonal points of the second step patterns and thesecond resist patterns formed by the second light on the second wafers.Drawing of the spreading portions of the second residual resists issimilar to the drawing of the spreading portions 57 a-57 d of the firstresidual resists shown in FIG. 5. Therefore, the drawing of thespreading portions of the second residual resists is omitted.

With reference again to FIG. 1, the CPU 100 further includes an exposuretool controller 326, a measurement module 322, and a density calculator327. Also, an exposure condition memory 338, a microscope 332, asimulator 301, and a polarization direction memory 336 are connected tothe CPU 100.

The exposure tool controller 326 controls the exposure conditions of theexposure tool 300. For example, the exposure tool controller 326instructs the reticle stage aligner 111 shown in FIG. 2 and the waferstage aligner 115 to move the reticle stage 11 and the wafer stage 15and set the placed position, a scanning direction, and a scanning speed.Moreover, the exposure tool controller 326 drives the polarizer holderrotator 66 to set the polarization direction of the polarizedillumination light irradiated from the light source 3. Therefore, thefirst light and the second light are defined by the polarizer holder 6and the polarizer holder, rotator 66. The exposure condition memory 338stores illumination conditions in the exposure tool 300 such as the NA,a coherence factor (σ) and an aperture type for annular or quadrupolarillumination. Moreover, the exposure condition memory 338 stores designdata of each reticle pattern of the first, second, and third testingreticles mounted on the reticle stage 11 of the exposure tool 300 shownin FIG. 2.

An atomic force microscope (AFM) and a scanning electron microscope(SEM) can be used for the microscope 332 shown in FIG. 1, for example.The microscope 332 obtains topographic images of the first resistpatterns on the first wafers 14 shown in FIGS. 11, 12, and 13 and thesecond resist patterns on the second wafers. The microscope 332transfers the topographic images to the data collector 321 as theinformation on the resist pattern formed over the step patterns.

The simulator 301 shown in FIG. 1 employs a Fourier transformationprogram which calculates light intensity of an image of the projectedreticle pattern and a string model to calculate a surface shape of theresist pattern in the developed resist. The simulator 301 models shapesof the first resist patterns 77 a-77 f, 87 a-87 d and 97 a-97 c shown inFIGS. 11, 12, and 13, respectively, by simulating each projection of thefirst, second, and third testing reticles shown in FIGS. 7, 8, and 9onto the first resist 30 shown in FIG. 10 with the first light. Also,the simulator 301 models shapes of the second resist patterns bysimulating each projection of the first, second, and third testingreticles shown in FIGS. 7, 8, and 9 onto the second resist with thesecond light. The simulator 301 transfers the simulated shapes of theresist patterns to the data collector 321 as the information on theresist patterns formed over the step patterns.

The measurement module 322 shown in FIG. 1 analyzes the topographicimage of the first resist patterns 77 a-77 f on the first wafer 14 shownin FIG. 11 which is obtained by the microscope 332. In a case wheresimulation results obtained by the simulator 301 are used, themeasurement module 322 shown in FIG. 1 analyzes surface shape data ofthe first resist patterns 77 a-77 f on the first wafer 14 shown in FIG.11 which is modeled by the simulator 301. By analyzing, the measurementmodule 322 shown in FIG. 1 measures each amount of the first residualresists “d₁”-“d₄” shown in FIG. 5 at each orthogonal point of the firststep pattern 16 shown in FIG. 11 and the first resist patterns 77 a-77f.

For example, in a case where the AFM or the SEM which is capable ofobtaining a three-dimensional topographic image is used as the microscope 332 shown in FIG. 1, the measurement module 322 executes a patternrecognition to identify the first step pattern 16 shown in FIG. 11 andthe first resist patterns 77 a-77 f based on a histogram of heightinformation of the topographic image. Further, the measurement module322 measures surface height from the orthogonal point of the first steppattern 16 and the first resist pattern 77 a to the edge of thespreading portion 57 a shown in FIG. 5 where the surface height is equalto the height of the first wafer 14. The measurement module 322 shown inFIG. 1 calculates a perpendicular distance between the edge of theresist pattern 77 a shown in FIG. 5 and the edge of the spreadingportion 57 a. The measurement module 322 defines the calculatedperpendicular distance as the amount of first residual resist “d₁”.Similarly, the measurement module 322 shown in FIG. 1 measures eachamount of first residual resists “d₂”-“d₄” shown in FIG. 5.

Also for the orthogonal points of the other first resist patterns 77b-77 f shown in FIG. 11 and the first step pattern 16, the measurementmodule 322 shown in FIG. 1 measures the amounts of the first residualresists “d₁”-“d₄” in a similar way. The measurement module 322calculates the average of the amounts of the first residual resists“d₁”-“d₄” at all orthogonal points on the first wafer 14 shown in FIG.11. The averaged amount of the first residual resists “d₁”-“d₄” aboutthe first resist patterns 77 a-77 f represents an effect of the firstlight polarized parallel to the first step pattern 16 in a case where aratio of the space “S₁” to each line width “L” of the first resistpatterns 77 a-77 f is one.

The measurement module 322 also analyzes the orthogonal points of thefirst resist patterns 87 a-87 d shown in FIG. 12 and the first steppattern 16. The measurement module 322 calculates the average of theamounts of the first residual resists “d₁”-“d₄” at all orthogonal pointson the first wafer 14. The averaged amount of the first residual resists“d₁”-“d₄” about the first resist patterns 87 a-87 d represents an effectof the first light in a case where a ratio of the space “S₂” to eachline width “L” of the first resist patterns 87 a-87 d is three.

Further, the measurement module 322 analyzes the orthogonal points ofthe first resist patterns 97 a-97 c shown in FIG. 13 and the first steppattern 16. The measurement module 322 calculates the average of theamounts of the first residual resists “d₁”-“d₄” at all orthogonal pointson the first wafer 14. The averaged amount of the first residual resists“d₁”-“d₄” about the first resist patterns 97 a-97 c represents an effectof the first light in a case where a ratio of the space “S₃” to eachline width “L” of the first resist patterns 97 a-97 c is six.

In a similar way, the measurement module 322 shown in FIG. 1 analyzesthe orthogonal points of the second resist patterns and the second steppattern. The measurement module 322 calculates the average of theamounts of the second residual resists “d₁”-“d₄” at all orthogonalpoints on the second wafer. The averaged amount of the second residualresists “d₁”-“d₄” about the second resist patterns formed by the firsttesting reticle shown in FIG. 7 represents an effect of the second lightpolarized perpendicular to the second step pattern in a case where aratio of the space to each line width of the second resist patterns isone. The averaged amount of the second residual resists “d₁”-“d₄” aboutthe second resist patterns formed by the second testing reticle shown inFIG. 8 represents an effect of the second light in a case where a ratioof the space to each line width of the second resist patterns is three.The averaged amount of the second residual resists “d₁”-“d₄” about thesecond resist patterns formed by the third testing reticle shown in FIG.9 represents an effect of the second light in a case where a ratio ofthe space to each line width of the second resist patterns is six.

Note that each ratio of the spaces “S₁”-“S₃” to each line width “L” ofthe first resist pattern 77 a-77 f, 87 a-87 d, and 97 a-97 c shown inFIGS. 11, 12, and 13 is an example. Therefore, the ratio is not limitedto the example and variable.

With reference next to FIG. 14, the residual resist analyzer 323 shownin FIG. 1 obtains the first relation between the ratio of the space “S”to each line width “L” of the first resist patterns and the averagedamount of the first residual resists “d₁”-“d₄”. Also, the residualresist analyzer 323 obtains the second relation between the ratio of thespace “S” to each line width “L” of the second resist patterns and theaveraged amount of the second residual resists “d₁”-“d₄”. Here, in acase where the ratio of the space “S” to each line width “L” of thefirst and second resist patterns is less than six, the averaged amount,of the second residual resists “d₁”-“d₄” is smaller than the averagedamount of the first residual resists “d₁”-“d₄”. On the contrary, in acase where the ratio of the space “S” to each line width “L” of thefirst and second resist patterns is six or more, the averaged amount ofthe first residual resists “d₁”-“d₄” is smaller than the averaged amountof the second residual resists “d₁”-“d₄”.

Note that measurement result shown in FIG. 14 is an example underexposure conditions where the NA is 0.68 and the coherence factor (σ) is0.75. When the exposure conditions are changed, the ratio of the space“S” to the line width “L” of the resist pattern also changes. Therefore,the polarization direction reducing the averaged amount of the residualresists “d₁”-“d₄” at certain ratio of the space “S” to each line width“L” of the resist patterns may change in accordance with the changes ofthe exposure conditions.

The direction chooser 324 shown in FIG. 1 chooses either the first lightor the second light as the optimum polarization direction reducing theaveraged amount of the residual resists “d₁”-“d₄” at certain ratio ofthe space “S” to each line width “L” of the resist patterns by comparingthe first relation and the second relation. In the example case shown inFIG. 14, the direction chooser 324 determines that the polarizationdirection perpendicular to the step pattern is the optimum polarizationdirection in the case where the ratio of the space “S” to each linewidth “L” of the resist patterns is less than six. Also, the directionchooser 324 determines that the polarization direction parallel to thestep pattern is the optimum polarization direction in the case where theratio of the space “S” to each line width “L” of the resist patterns issix or more.

The polarization direction memory 336 stores a combination of the ratioof the space “S” to each line width “L” of the resist patterns and theoptimum polarization direction determined by the direction chooser 324.

The density calculator 327 reads the design data of the reticle patternstored in the exposure condition, memory 338. The density calculator 327extracts an area of the projected reticle pattern of which longerdirection is perpendicular to the longer direction of the step pattern.Further, the density calculator 327 calculates the ratio of the space“S” to the line width “L” of the projected reticle pattern.

With reference again to FIG. 1, an input unit 312, an output unit 313, aprogram memory 330, and a temporary memory 331 are also connected to theCPU 300. A keyboard and a mouse may be used for the input unit 312. AnLCD or an LED may be used for the output unit 313. The program memory330 stores a program instructing the CPU 300 to transfer data withapparatuses connected to the CPU 300. The temporary memory 331 storestemporary-data calculated during operation by the CPU 300.

With reference next to FIG. 15, a method for manufacturing asemiconductor device according to the embodiment of the presentinventions is described.

In step S10, the first wafers 14 shown in FIG. 10 are prepared. On eachof the first wafers 14, the first step pattern 16 is disposed and thefirst resist 30 is coated over the first step pattern 16. In step S11,one of the first wafers 14 is inserted into the exposure tool 300 shownin FIG. 2. In step S12, the first testing reticle shown in FIG. 7 ismounted on the reticle stage 11 shown in FIG. 2 so that each longerdirection of the transparent portions 80 a-80 f shown in FIG. 7 isperpendicular to the longer direction of the first step pattern 16 shownin FIG. 10. Thereafter, the exposure tool 300 shown in FIG. 2 projectsthe image of the transparent portions 80 a-80 f shown in FIG. 7 onto thefirst resist 30 shown in FIG. 10 with the first light.

In step S13, other one of the first wafers 14 is inserted into theexposure tool 300 shown in FIG. 2. The second testing reticle shown inFIG. 8 is mounted on the reticle stage 11 so that each longer directionof the transparent portions 81 a-81 e is perpendicular to the longerdirection of the first step pattern 16. Thereafter, the exposure tool300 projects the image of the transparent portions 81 a-81 e onto thefirst resist 30 with the first light.

In step S14, yet other one of the first wafers 14 is inserted into theexposure tool 300 shown in FIG. 2. The third testing reticle shown inFIG. 9 is mounted on the reticle stage 11 so that each longer directionof the transparent portions 82 a-82 d is perpendicular to the longerdirection of the first step pattern 16. Thereafter, the exposure tool300 projects the image of the transparent portions 82 a-82 d onto thefirst resist 30 with the first light.

In step S15, each first resist 30 is developed by developer solution toform the first resist patterns 77 a-77 f, 87 a-87 d, and 97 a-97 c shownin FIGS. 11, 12, and 13 corresponding to the first, second, and thirdtesting reticles shown in FIGS. 7, 8, and 9, respectively. As shown inFIG. 11, each of the first resist patterns 77 a-77 f has the line-width“L” and is spaced apart “S₁” in parallel. As shown in FIG. 12, each ofthe first resist patterns 87 a-87 d has the line width “L” and spacedapart “S₂” in parallel. As shown in FIG. 13, each of the first resistpatterns 97 a-97 c has the line width “L” and spaced apart “S₃” inparallel. Each longer direction of the first resist patterns 77 a-77 f,87 a-87 d, 97 a-97 c is perpendicular to the longer direction of thefirst step pattern 16 on the first wafer 14.

In step S16, the microscope 332 shown in FIG. 1 obtains the topographicimages of the first resist patterns 77 a-77 f, 87 a-87 d, and 97 a-97 cshown in FIGS. 11, 12, and 13. Thereafter, the data collector 321transfers the topographic images from the microscope 332 to themeasurement module 322. The measurement module 322 measures the amountof the first residual resists “d₁”-“d₄” shown in FIG. 5 at theorthogonal point of the first step pattern 16 and each of the firstresist patterns 77 a-77 f, 87 a-87 d, and 97 a-97 c shown in FIGS. 11,12, and 13. Subsequently, the measurement module 322 calculates theaveraged amount of the first residual resists. Then, the residual resistanalyzer 323 obtains the first relation between the ratio of the space“S” to each line width “L” of the first resist patterns and the averagedamount of the first residual resists.

In step S17, the second, wafers are prepared. On each of the secondwafers, the second step pattern is disposed and the second resist iscoated over the second step pattern. The shape of the second steppattern is similar to the shape of the first step pattern 16 shown inFIG. 10. In step S18, one of the second wafers is inserted into theexposure tool 300 shown in FIG. 2.

In step S19, the first testing reticle shown in FIG. 7 is mounted on thereticle stage 11 shown in FIG. 2 so that each longer direction of thetransparent portions 80 a-80 f shown in FIG. 7 is perpendicular to thelonger direction of the second step pattern. Thereafter, the exposuretool 300 shown in FIG. 2 projects the image of the transparent portions80 a-80 f shown in FIG. 7 onto the second, resist with the second light.

In step S20, other one of the second wafers is inserted into theexposure tool 300 shown in FIG. 2. The second testing reticle shown inFIG. 8 is mounted on the reticle stage 11 so that each longer directionof the transparent portions 81 a-81 e is perpendicular to the longerdirection of the second step pattern. Thereafter, the exposure tool 300projects the image of the transparent portions 81 a-81 e onto the secondresist with the second light.

In step S21, yet other one of the second wafers is inserted into theexposure tool 300 shown in FIG. 2. The third testing reticle shown inFIG. 9 is mounted on the reticle stage 11 so that each longer directionof the transparent portions 82 a-82 d is perpendicular to the longerdirection of the second step pattern. Thereafter, the exposure tool 300projects the image of the transparent portions 82 a-82 d onto the secondresist with the second light.

In step S22, each second resist is developed by developer solution toform the second resist patterns. The second resist patterns are similarto the first resist patterns 77 a-77 f, 87 a-87 d, 97 a-97 c shown inFIGS. 11, 12, and 13 corresponding to the first, second, and thirdtesting reticles shown in FIGS. 7, 8, and 9, respectively. Each of thesecond resist patterns has the line width “L” and is spaced apart “S₁”,“S₂”, and “S₃”, respectively. Each longer direction of the second resistpatterns is perpendicular to the longer direction of the second steppattern on the second wafer.

In step S23, the microscope 332 shown in FIG. 1 obtains the topographicimages of the second resist patterns. Thereafter, the data collector 321transfers the topographic images from the microscope 332 to themeasurement module 322. The measurement module 322 measures the amountof the second residual resists “d₁”-“d₄” at the orthogonal point of thesecond step pattern and each of the second resist patterns as similar tothe first resist patterns. Then, the measurement module 322 calculatesthe averaged amount of the second residual, resists. Subsequently, theresidual resist analyzer 323 obtains the second, relation between theratio of the space “S” to each line width “L” of the second resistpatterns and the averaged amount of the second residual resists.

In step S24, the direction chooser 324 compares the first relation andthe second relation to determine the optimum polarization direction ofthe illumination light that reduces, the amount of residual resists“d₁”-“d₄”. Then, the direction chooser 324 stores the optimumpolarization direction at the certain ratio of the space “S” to eachline width “L” of the resist patterns in the polarization directionmemory 336.

In step S100, the third wafer is prepared. On the third wafer, the thirdstep pattern is disposed and the third resist is coated over the thirdstep pattern. In step S101, the third wafer is mounted on the waferstage 15 shown in FIG. 2 in the exposure tool 300. In step S102, thedensity calculator 327 reads the design data of a device pattern of areticle for manufacturing the semiconductor device stored in theexposure condition memory 338. The density calculator 327 extracts thearea of the projected reticle pattern of which longer direction isperpendicular to the longer direction of the third step pattern.Subsequently, the density calculator 327 calculates the ratio of thespace “S” to the line width “L” of the projected reticle pattern. Then,the exposure tool controller 326 refers to the polarization directionmemory 336 for the optimum polarization direction reducing the amount ofthe residual resists “d₁”-“d₄” at the orthogonal point of third steppattern and the projected reticle pattern based on the calculated ratioof the space “S” to the line width “L” of the projected reticle pattern.

In step S103, the exposure tool controller 326 adjusts the polarizerholder 6 so that the polarization direction of the illumination lightreduces the amount of the residual resists. In step S104, the exposuretool 300 projects the device pattern onto the third resist on the thirdwafer. In step S105, the third resist is developed by developer solutionto form the third resist pattern of which longer direction isperpendicular to the longer direction of the third step pattern on thethird wafer. Thereafter, the insulating film formation and the circuitlayer formation are repeated until the manufacturing of thesemiconductor device is completed.

With reference next to FIG. 16, a method for manufacturing thesemiconductor device in a case where the simulator 301 shown in FIG. 1is used is described.

In step S40, the simulator 301 simulates each projection of thetransparent portions 80 a-80 f shown in FIG. 7, the transparent portions81 a-81 e shown in FIG. 8, and the transparent portions 82 a-82 d shownin FIG. 9 onto the first resist 30 shown in FIG. 10 with the firstlight. Subsequently, the simulator 301 simulates the development of thefirst resist 30 to model the shape of the first resist patterns 77 a-77f, 87 a-87 d, and 97 a-97 c shown in FIGS. 11, 12, and 13 correspondingto the first, second, and third testing reticles shown in FIGS. 7, 8,and 9, respectively. The simulator 301 shown in FIG. 1 stores thepredicted shapes in the temporary, memory 331.

In step S41, the data collector 321 transfers the predicted shape fromthe temporary memory 331 to the measurement module 322. The measurementmodule 322 measures the amount of first residual resists “d₁”-“d₄” shownin FIG. 5 at the orthogonal point of the first step pattern 16 and eachof the first resist patterns 77 a-77 f, 87 a-87 d, and 97 a-97 c basedon the predicted shapes. Subsequently, the measurement module 322calculates the averaged amount of the first residual resists. Then, theresidual resist analyzer 323 obtains the first relation between theratio of the space “S” to each line width “L” of the first resistpatterns and the averaged amount of the first residual resists.

In step S42, the simulator 301 simulates each projection of thetransparent portions 80 a-80 f shown in FIG. 7, the transparent portions81 a-81 e shown in FIG. 8, and the transparent portions 82 a-82 d shownin FIG. 9 onto the second resist with the second, light. Subsequently,the simulator 301 simulates the development of the second resist tomodel the shape of the second resist patterns. The simulator 301 storesthe predicted shapes of the second resist patterns in the temporarymemory 331.

In step S43, the data collector 321 transfers the predicted shape fromthe temporary memory 331 to the measurement module 322. The measurementmodule 322 measures the amount of the second residual resists “d₁”-“d₄”at the orthogonal point of the second step pattern and each of thesecond resist patterns based on the predicted shapes. Subsequently, themeasurement module 322 calculates the averaged amount of the secondresidual resists. Then, the residual resist analyzer 323 obtains thesecond relation between the ratio of the space “S” to each line width“L” of the second resist patterns and the averaged amount of the secondresidual resists.

In step S44, the direction chooser 324 compares the first relation andthe second relation to determine the optimum polarization direction ofthe illumination light that reduces the amount of residual resists“d₁”-“d₄”. Then, the direction chooser 324 stores the optimumpolarization direction at the certain ratio of the space “S” to eachline width “L” of the resist patterns determined by the directionchooser 324 in the polarization direction memory 336. Thereafter, stepsS100-S105 are carried out as similar to the methods shown in FIG. 15.

As described above, the polarization analyzing system shown in FIG. 1determines the optimum polarization direction based on the patterndensity of the resist pattern expressed as the ratio of the space “L” tothe line width “S” in the case where the resist pattern is formed on thestep pattern on the wafer and the longer direction of the resist patternis perpendicular to the longer direction of the step pattern.Accordingly, the polarization analyzing system makes it possible toeffectively reduce the amount of residual resists “d₁”-“d₄” shown inFIG. 5 at the orthogonal point of the step pattern and each of theresist patterns.

In earlier methods, in a case where the resist coated on the steppattern is exposed to the illumination light, it has been assumed thatconfining the oscillation of the linearly polarized light to thedirection perpendicular to the longer direction of the step patternreduces the scattering of the illumination light on the wafer. Therefore, the oscillation of the linearly polarized light is always confinedto the direction perpendicular to the longer direction of the steppattern.

However, the polarization analyzing system shown in FIG. 1 does notalways only use the polarized light of which polarization direction isperpendicular to the longer direction of the step pattern. Thepolarization analyzing system shown in FIG. 1 also use the polarizedillumination light of which polarization direction is parallel with thelonger direction of the step pattern based on the ratio of the space “L”to each line width “S” of the resist patterns to be formed. Therefore,the polarization analyzing system makes it possible to preciselyreproduce the designed circuit pattern on the wafer even at theorthogonal point of the step pattern and each of the resist patterns.

Further, by storing a database of combinations of the optimumpolarization direction and the ratio of the space “L” to each line width“S” of the resist patterns in the polarization direction memory 336, itis possible to instantly select the appropriate polarization directionwhen the reticle pattern is projected onto the resist. It should benoted that the order to carry out the steps of the method formanufacturing the semiconductor device shown in FIGS. 15 and 16 ischangeable.

(Modification)

In the embodiment, the polarizer shown in FIG. 3 or FIG. 4 is insertedto the polarizer holder 6 shown in FIG. 2. However, type of thepolarizer is not limited to the polarizer shown in FIG. 3 or FIG. 4. Forexample, the polarizer shown in FIG. 17 or FIG. 18 also can be used. Thepolarizer shown in FIG. 17 has a plate 44 and a plurality of circularpolarizing filters 45 a, 45 b, 45 c, 45 d, 45 e, 45 f, 45 g, and 45 hprovided in the plate 44. The polarizing filters 45 a-45 h are locatedaround the center of the plate 44. The polarizing filters 45 a-45 h areoriented so that the illumination light is polarized radially away fromthe optical axis.

The polarizer shown in FIG. 18 has a plate 44 and a plurality ofcircular polarizing filters 46 a, 46 b, 46 c, 46 d, 46 e, 46 f, 46 g,and 46 h provided in the plate 44. The polarizing filters 46 a-46 h areoriented so that the illumination light is azimuthally polarized. Withreference to FIG. 19, an optical effect in a case where the polarizershown in FIG. 17 is used is described. In FIG. 19, a polarizer 60including the plate 44 and the plurality of polarizing films 45 a-45 hprovided in the plate 44, a reticle 10 including a plurality oftransparent portions 50 a, 50 b, 50 c, 55 a, 55 b, and 55 c disposedbeneath the polarizer 60, a projection optical system 13 disposedbeneath the reticle 10, and a wafer 20 coated with a resist 22 disposedbeneath the projection optical system 13 are illustrated.

The transparent portions 50 a-50 c provided in the reticle 10 arearranged along an “X” direction, whereas the transparent portions 55a-55 c provided in the reticle 10 are arranged along a “Y” directionperpendicular, to the “X” direction.

In this case, polarized illumination lights transmitted through thepolarizing films 45 a and 45 e located along the “Y” direction primarilycontribute to a projection of an image of the transparent portions 50a-50 c along with the “X” direction onto the resist 22 and a formationof the projected images 150 a, 150 b, and 150 c. Other polarizedillumination lights transmitted through the polarizing films 45 b-45 dand 45 f-45 h penetrate the transparent portions 50 a-50 c and zeroorder diffracting light is generated at the transparent portions 50 a-50c. The zero order diffracting light contributes to the formation of theprojected images 150 a, 150 b, and 150 c as a bias component. However,intensity of the zero order diffracting light is too weak. Therefore, acontribution of the zero order diffracting light to the formation of theprojected images 150 a and 150 b is negligible.

On the other hand, polarized illumination lights transmitted through thepolarizing films 45 c and 45 g located along the “X” direction primarilycontribute to a projection of an image of the transparent portions 55a-55 c along with the “Y” direction onto the resist 22 and a formationof the projected images 155 a, 155 b, and 155 c. The intensity of otherpolarized illumination lights transmitted through the polarizing films45 a, 45 b, 45 d-45 f, and 45 h is too weak. Therefore, a contributionof the other polarized illumination lights to the formation of theprojected images 155 a-155 c is negligible.

Therefore, the projected images 150 a-150 c along with the “X” directionare formed by the illumination light polarized parallel with the “Y”direction. The projected images 155 a-155 c along with the “Y” directionare formed by the illumination light polarized parallel with the “X”direction.

Accordingly, in a case where a step pattern along with the “Y” directionis disposed on the wafer 20 and the projected images 150 a-150 c areformed over the step pattern along with the “Y” direction, the projectedimages 150 a-150 c along with the “X” direction are formed by the firstlight which is polarized such that the electric field of theillumination light is parallel to the longer direction of the steppattern along with the “Y” direction. Further, in a case where a steppattern along with the “X” direction is disposed on the wafer and theprojected images 155 a-155 c are formed over the step pattern along withthe “X” direction, the projected images 155 a-155 c along with the “Y”direction are also formed by the first light which is polarized suchthat the electric field of the illumination light is parallel to thelonger direction of the step pattern along with the “X” direction.

Consequently, in a case where all projected images 150 a-150 c andprojected images 155 a-155 c are spaced apart “S” corresponding to alength that the first light reduces the residual resists at theorthogonal points of the step patterns and the resist patterns formed bydeveloping the resist 22, the polarizer 60 makes it possible toeffectively reduce the amount of the residual resists even though thestep pattern beneath the projected images 150 a-150 c is perpendicularto the step pattern beneath the projected images 155 a-155 c. Also, in acase where all projected images 150 a-150 c and 155 a-155 c are spacedapart “S” corresponding to a length that the second light reduces theresidual resists, the polarizer shown in FIG. 18 makes it possible toeffectively reduce the amount of residual resists.

With reference next to FIG. 20, a method for manufacturing thesemiconductor device according to the modification of the embodiment isdescribed.

In step S201, the step patterns are formed on the wafer 20 shown in FIG.19. Then, the resist 22 is coated over the step patterns on the wafer20. In step S202, the wafer 20 is mounted on the wafer stage 15 shown inFIG. 2 in the exposure tool 300. In step S203, the reticle 10 shown inFIG. 19 is mounted on the reticle stage 11 shown in FIG. 2. In thiscase, the step pattern along with the “X” direction is located beneath afield where the projected images 155 a-155 c shown in FIG. 19 are to beprojected. Also, the step pattern along with the “Y” direction islocated beneath a field where the projected images 150 a-150 c are to beprojected.

In step S204, the density calculator 327 shown in FIG. 1 reads thedesign data of the reticle pattern stored in the exposure conditionmemory 338. Then, the density calculator 327 extracts the area of theprojected image of the reticle pattern of which longer direction isperpendicular to the longer direction of the step pattern on the wafer.Subsequently, the density calculator 327 calculates the ratio of thespace “S” to the line width “L” of the extracted projected image of thereticle pattern. The exposure tool controller 326 refers to thepolarization direction memory 336 for the optimum polarization directionreducing the amount of the residual resists “d₁”-“d₄” at the orthogonalpoint of the step patterns and the projected reticle pattern based onthe calculated ratio of the space “S” to the line width “L” of theprojected reticle pattern.

In step S205, in a case where the first light is chosen in the stepS204, the polarizer shown in FIG. 17 is inserted to the polarizer holder6 shown in FIG. 2. Thereafter, the illumination light is emitted fromthe light source 3 and the illumination light is polarized radially awayfrom the optical axis in the exposure tool 300.

In step S206, in a case where the second light is chosen in the stepS204, the polarizer shown in FIG. 18 is inserted to the polarizer holder6 shown in FIG. 2. Thereafter, the illumination light is emitted fromthe light source 3 and the illumination light is azimuthally polarized.Thereafter, steps S207 and S208 are carried out as similar to the stepsS104 and S105 shown in FIG. 15.

As described above, the method for manufacturing the semiconductordevice shown in FIG. 20 makes it possible to project the image of thetransparent portions 50 a-50 c and 55 a-55 c shown in FIG. 19 onto theresist 22 by the illumination light polarized in the optimumpolarization direction, even thought the transparent portion 50 a-50 care arranged in perpendicular to the transparent portions 55 a-55 c andthe step patterns are perpendicular to the projected images 150 a-150 cand the projected images 155 a-155 c.

Other Embodiments

Although the invention has been described above by reference to theembodiment of the present invention, the present invention is notlimited, to the embodiment described above. Modifications and variationsof the embodiment described above will occur to those skilled in theart, in the light of the above teachings.

For example, in the steps S102 to S105 shown in FIG. 15, the densitycalculator 327 extracts the area of the projected reticle pattern ofwhich longer direction is perpendicular to the step pattern andcalculates the ratio of the space “S” to the line width “L” of theprojected reticle pattern. Then, the optimum polarization direction ischosen to project the image of the reticle pattern.

However, there is a case where the ratio of the space “S” to the linewidth “L” of the projected reticle pattern is not even. In this case,both of a field where the first light is effective in reducing theresidual resists and a field where the second light is effective mayexist on the same wafer. To solve such problem, dividing the design dataof the reticle pattern into two regions is an alternative. One of theregions contains a part of the reticle pattern where the first light iseffective. Another one of the regions contains, a part of the reticlepattern where the second light is effective. Then, a first reticleincluding the reticle pattern where the first light is effective and asecond reticle including the reticle pattern where the second light iseffective are manufactured. After an image of the first reticle isprojected onto the resist by the first light, an image of the secondreticle is projected onto the same resist. Consequently, it is possibleto re-produce the designed circuit pattern on the resist even though theratio of the space “S” to the line width “L” of the projected reticlepattern is not even. It should be noted that the order to project theimages of the first and second reticles is changeable.

Moreover, providing two patterns on a reticle is another alternative.Specifically, the reticle including a first reticle pattern where thefirst light is effective and a second reticle pattern where the secondlight is effective is manufactured. After the reticle is mounted on thereticle stage 11, the exposure tool 300 projects an image of the firstreticle pattern onto the resist. Thereafter, the reticle stage 11 ismoved by the reticle, stage aligner 111. Subsequently, the exposure tool300 projects an image of the second reticle pattern onto the sane,resist.

As described above, the present invention includes many variations ofembodiments. Therefore, the scope of the invention is defined withreference to the following claims.

1. A polarization analyzing system comprising: a data collectorconfigured to collect an information on resist patterns formed over steppatterns disposed on wafers by first and second lights, respectively,the resist patterns being perpendicular to the step patterns, the firstand second lights being polarized parallel and perpendicular to the steppatterns, respectively; a residual resist analyzer configured to obtainfirst and second relations between a ratio of a space to a line width ofthe resist patterns and first and second residual resists on the wafers,respectively, the first and second residual resists remaining atorthogonal points of the step patterns and the resist patterns formed bythe first and second lights, respectively; and a direction chooserconfigured to choose an optimum polarization direction reducing residualresists by comparing the first and second relations.
 2. The system ofclaim 1, further comprising a microscope configured to observe the firstand second residual resists.
 3. The system of claim 1, furthercomprising a simulator configured to model shapes of the first andsecond residual resists.
 4. The system of claim 1, further comprising anexposure condition memory configured to store design data of a reticlepattern for manufacturing a semiconductor device.
 5. The system of claim4, further comprising a density calculator configured to calculate aratio of a space to a line width of a projected image of the reticlepattern.
 6. The system of claim 5, further comprising an exposure toolconfigured to project the reticle pattern onto a resist by using a lightpolarized in the optimum polarization direction. 7.-14. (canceled)